Refining hydrocarbon oils



April 29, 1930. E. c. HERTHELKET AL v REFINING HYDROCARBNy OILS Filed June 16, 1928 Y constituents Treatments of the raw stock supplied to and Patented Apr. 29, 1930 UNITED STATES PATENT OFFICE.

EUGENE C. HERTHEL, OF CHICAGO, ILLINOIS, AND HARRY L. PELZER, OF HIGHLAND, INDIANA, ASSIGNORS TO SINCLAIR REFINING COMPANY, OF NEW YORK, N. Y., A

CORPORATION OF MAINE Application led June 16,

This invention relates to improvements in the manufacture of lubricating oils', and provides an improved method of producing lubricating oils from oils containing v,lubricating oil fractions, such as crude petroleum oils, topped crude oils, and the like. The invention is oflspecial value and application in the manufacture of lubricating oils from certain types of crude oils or. crude oil stocks of which the Gulf coast, south Texas and the California oils may be taken as examples.

In general, -lubricating oils may be defined as oils heavier thah gas oil, heavier than'about '35 B., and having viscosities upwards of about at 100 F. Saybolt Universal.

There is a group of constituents, apparently characteristic of naphthene base crude oils, which are extremely objectionable as components of lubricating oils in particular. These constituents are particularly objectionable in that they render unstable lubricatingl oils in which they are present. They also impair the quality of lubricating oils containing them in other respects, color forexample.

As yet, this group of objectionable constit uents has not been definitely identified. These objectionable constituents are themselves apparently of relatively low boiling point, yet they polymerize quite readily-'to form a tar or tarry substance. -This polymerization is promoted, for example, by the presence of air or steam. With certain types of stocks, additional quantities-of these objectionable constituents seem to be formed as long as the oil is maintainedat elevated temperature, this effect increasing with temperature fincrease.

A number of yschemes of procedure have been proposed intended to avoid the objectionable incidents of the presence of this group of objectionable constituents in lubrieating oils, but these proposals have not been entirely satisfactory;in some cases because of operating difficulties and in other cases because of failure to reach the real diiiiculty. Treatments of the raw stock preceding distillation have been proposed; such treatments are not effective with respect to objectionable formed during distillation.

BEFINING HYDROCARBON OILS 1928. y Serial No. 285,821.

co-incidental lwith distillation have been proposed; in shell still distillations coke troubles have been encountered with crude stocks andin pipe still distillation corrosion difliculties have been encountered. In practice, the expedient most generally adopted has been to rerun the lubricating oil distillate fraction or fractions over caustic alkali but this scheme likewise is not entirely satisfactory; additional distillation operations are required, in some cases the lubricating oil distillate .fraction must be rerun a second or third time, and rerunning subjects the lubri eating oil to-elevated temperatures over further prolonged periods cf time. For the most part previous proposals further have been defective in the proper application of and it also has advantages when combined with operations including acid refining.

The present invention provides an improved method of producing lubricating oils from oils containing lubricating oil fractions in which a treatment lwith caustic alkali is combined with a fractionating operation in a particularly advantageous mannelgand in a inanner particularly advantageous with respect to elimination of constituents ofthe objectionable group noted above in cases where such objectionable constituents are, present.

In carrying out the present invention, a streamof stock containing lubricating oil constituents is flowed through a heating zone into a lvapor separating zone, the stock is heated to a relatively low vaporizing temperature in the heating zone, the vapors separated in the vapor separat-ing zone, including the lubricating oil constituents, are caused to bubble through a hot liquid oil bath maintained. alkaline by supplying causticalkali thereto, the vapors including the lubricating oil constituents escaping from the hot alkaline bath are subjected to a fractionating operation in which higher boiling constituents are condensed, the remaining vapors including the lubricating oil constituents are taken oli from this tractionating operation and a lubricating oil fraction or a series of lubrieating oil fractions is condensed therefrom.

objectionable decomposition in the heating zone is avoided by limiting the time of passage of the oil through the heating zone and by limiting the tcniperature to which the oil is heated therein. ln the vapor separating zone the vaporization of the lubricatingr oil constituents is With advantage promoted by the introduction of a distillation medium, superheated steam or some other superheated gaseous medium for example. This distillation medium is with advantage supplied at a temperature higher than that at which the oil leaves the heating zone. i The expression i gaseous distillation medium as used in the appended claims is not intended to designate any particular class ot gaseous materials having a particular common property pe-.

culia-r to the class. It refers merely to the relatively inactive gaseous materials, of which superheated steam may be considered an example, which do not have a deleterious effect upon oil but which by virtue ofthe fact that they ez'iistin a gaseous state are used in a manner Well known to the art to assist in the distillation of oils by reducing the partial pressure of the oil vapors in accordance with the Well known fundamental principles of partial pressures generally known as Daltons law. The introduction of steam at this point has certain special advantages noted below. The vapor separation may be carried out coincidentally With the alkaline treatment; it is advantageous, however, to separate these operations first carrying out the. vapor 'separation and taking off vapors including the lubricating oil constituents therefrom and thensubjecting these vapors including the lubricating oil constituents to the alkaline treatment. l

By carrying out the heating and Vaporizing operations as-just described, the heating operation is carried. out efficiently and vaporization of even the heavier lubricating-oil constituents is effected while subjecting the oil containing these lubricating oil constituents to high temperatures for but a minimum time. A distillation medium may be passed through the heating zone with theraw stock but it is more advantageously introduced into the vapor separating zone Where'it is none the less eiective in promoting vaporization of the lubricating oil constituents with-. out interfering with the `heating' operation. Objectionable decomposition due to local overheating is avoided by maintaining rapid; flow through the heating zone, by carrying' out the vapor separation in an externally unheated zone, and by utilizing a distillation medium.

avoid condensation of any constituents of tht` The hot alkaline treatment is with advantage carried out as described in our co-pending application filed June 16,1928, Serial No. 285,820.

In the hot liquid alkaline oil bath, the lubrieating oil constituents are subjected as vapors to intimate contactwith caustic alkali. The caustic alkali neutralizes acidic constituents of the oil vapors and, apparently, also acts as a polymerizing agent promoting the polymerization of constituents of the objectionable group 'noted above. Steam used as a m distillation' medium in the vapor separation also assists in this polymerization and in some cases seems to make the caustic alkali-more 50 active. In any event, it is necessary, to secure the advantages of the invention, to fractionally condense higher boiling constituents from the vapors including the lubricating oil constituents escaping from the hot alka` 85 line treatment before condensing the lubricating oil product or products. The high boiling constituents separated in this frac- `tionating operation following the hot alkaline treatment and preceding condensation of the lubricating oil include reaction products ofthe hot alkaline treatment and the products of polymerization of any objectionable constituents present. Where the vapor separation and the alkaline treatment are carried lout co-incidentally, these reaction products and polymerization products may be separated with the residuum from the distillation; Where the alkaline treatment is carried out separately from vand subsequent to the. vapor separation these reaction products and polymerization products may be sepa-- rated as a separate caustic tar representing but/a minor proportion ot' the' total residuum.

The caustic alkali is advantageously supplied to the treating bath as a concentrated aqueous solution; when so supplied the Water is evaporated from the bath leaving the alkali in suspension in a fine state of division throughout the bath. It is important that suilicient alkali be supplied to maintain the treating bath alkaline throughout the operation. j

Following fractional condensation of high boiling constituents, including t-hese reaction products and polymerization products', from the vapors including the lubricating oil constituents, the lubricating voil constituents may' be condensed, as a lubricating'oil fraction or as a series of lubricating oil fractions. This" separationot the lubricating oil product or products is also with advantagecarried out by fractional condensation controlled to objectionable group noted above remaining.125 in low boiling form or formed inthe vapor l` mixture after leaving the fractionating operation preceding .the first separation ,of a lubricating oil product. j

The invention will be further described in connection with the accompanying drawings -which illustrate, diagrammaticlly and conventionally, one form of apparatus adapted vapor separat-ing tower 3. unvaporized resi-. due is discharged through cooler 10, the separated vapors escape from the upper end oftower 3 to the lower end of treating and fractionatingtower 4 through connection 17, vapo-rs escape from the upper end of tower 4 to the lower end of tower 5 and lso on through towers 6, 7 and. 8,.the condensates separated in each of towers 5, 6, 7 and 8 are severally discharged throughcoolers 12,. 13, 14 and 15 respectively,.and vapors yescaping from the' upper end of tower 8 are passed through condenser 9 where they are subjected to filial condensation. Steam is supplied to superheater v1 through connection 18, or other gaseous distillation medium ma be supplied through connection 19. The ischarge connection 2O from the superheater 1 is provided with valved-branch connections 43, 44, 45. 46. 47

and '48 for the introduction of the Y distilla- .tion medium into the lower ends of the several v towers as may be required. Cooling'coils 23, l

2 4, 25,26, 27 and 28 are provided in the upper' ends of the several towers; raw stock to be Vsupplied to the operation,v for example, may be circulated through these coils in series or in parallel on its way to the oil heater. Cool- Icoils 33, 34, 35, 36, 37 and 38 are also proin vided in the upper ends of the several towers ysome supplementary refluxing or controlling cooling medium. water for example, may be circulated through thesecoils. By .providing a pair of cooling coils in the upper end 'of each tower, as just described, the major part of the heat to be removed from the upper end of each tower can be absorbed in raw stock to be supplied to the operation and exact control can be had by regulation of the rate of circulation or the temperature ot' the Asupplementary reuxing or cooling medium.

Thelo'il heater 2 may be of conventional pipe still 'construction'. To avoid local overheat.- ing in particular, part of the escaping waste heating gases may he recirculated through the heatingflues in admixture with fresh hot products of combustion from the irebox. In the oil heater illustrated, the return flue for recirculation of heating gases is divided into two branches 29 and 3()` provided with dampers as illustrated, to permit the reintroduction of the recirculated heating gases,

'or'part ofthem, at an intermediate point in the furnace so that .the bulk of the recircula-A tion is effected across the heating tubes exposed to the hottest heating gases. The oil heater discharges into the vapor separating tower 3 at a point somewhat above its lower end to afford an opportunity for, complete separation o't vaporized constituents from unvaporized residual oil. Abovev this point ot introduction, the vapors are subjected to a fractionating operation for the separation' of very heavy constituents, tars and the like. The vapor separating tower 3 may be bypassed by means of connection and the vapor separation and the treating and fractionating operations carried out together in tower 4,' but this usually is less advantageous.

Vapor connection 17 from the upper end of tower`3 to the lower end of tower 4 terminates in a normally submerged inlet pipe 21 for the introduction of the vapors beneath the normal liquid level in the lower end of tower 4, and connection 22 is provided for the introduction, into'the vapors flowing through connection 17 and ipe 21, of caustic alkali. Vapors escaping rom the. upper end of tower 7 are discharged into tower 8 at a point somewhat above its lower end, the vapors being subjected to a fractionating operation above the point of introduction and the condensate being subjected to a stripping operation for the separation of low boiling constituents below the point of introduction. Superheated lsteam or other hot gaseous medium is supplied to the lower ends of towers 5, 6, 7 and 8 to control, .in conjunction with controlled cooling at the upper ends of these towers, the fractionating operations carried out-therein. Superheated steam or other hot gaseous" medium is supplied to the lower end of tower 3 through connection 43, beneath the stripping section, and to the lower end. of tower 4 through connection 44 as a distillation medium as Well as a control medium. and in the case of steam also as a treating agent. Tower 3 may be of open battle construction or of so-called bubble plate construction. vTowers 4, 5, 6,7 and 8 are with advantage of bubble plate or other construction adaptedto secure close fractionation. The several towers, particularly towers 3 and 4, andthe vapor connections between themyare with advantage lagged or thermally insulatedto minimize heat loss. I l i In carrying out the invention in the apparatus illustrated, the raw stock containvpipe still to carry out this heating, the time during which the oil is passing throngh the heating; operation 1s usually less in minutes than is the time in hours where shell stills are used for vaporization. The time of passage through the pipe still, -for example, may be limited not to exceed 10 or 15 minutes, as compared to periods upwards ot' 10 hours in shell stills. ln the fractionatiug tower 3, the 'lubricating oil constituents are separated or vaporized and separated from the unvaporized residual oil andthe latterdischarged through cooler l0. To prol'uote this vaporization and separation, supelheated steam, at temperatures in the neighborhood of 800- 000 l". tor example, or other distillation medium. is supplied through connection 43. The operation of tower 3, as well as the opf eration of the remaining towers 4, 5, 6, 7 -and 8. is controlled by regulated cooling at the upper end of the tower and by regulated heating at the lower end of the tower. The vapors containing lubricating oil constituents escapingr from the upper end of tower 3 through line 17 are bubbled through a hot liquid oil bath maintained in the lower end of tower`4, being introduced beneath the liquid level thereof through pipe 2l. This hot oil bath is maintained alkaline b v supplying caustic alkali thereto through connection 22 and pipe 21.' This oil bath is maintained at a temperature sufficiently high to maintain in vapor phase the constituents of the desired lubricating oil products. The vapors escaping from this treating bath, including the lubricating oil constituents, are subjected to closely controlled fractionation as they flow upwardly through tower 4. The liquid treating bath in the lower end of tower 4 is with advantage maintained of substantially constant volume as the operation proceeds. Any tendency of the bath to decrease in Volume may be counteracted by supplying the caustic alkali at a lower temperature, by cooling or increasing 'the cooling of the vapors in the upper end of they tower. by decreasing the rate of liquid discharge through cooler 11, or by decreasing the rate at which steam or other heating medium is supplied to the lower end of the tower. Any tendency of the bath to increase in volume may be counteracted by supplying the caustic alkali at a higher temperature, by decreasing the 'cooling of the vapors inthe upper end of the tower, by increasing the rate of liquid discharge, or by supplying steam or increasing the supply of steam, or other heating medium, to the lower'end of the tower. The vapors in the upper end of the tower 4 are cooled suliiciently to condense all tarry constituents or other high boiling constituents, including polymerization products and reaction products of the alkaline treatment, not suitable as components of the desired lubricating oil; products. In the towers 5, 6, 7- and 8 the vapors escaping from the upper end of tower 4 are subjected to fractional condensation to separate and condense therefrom a series of progressively lighter and less viscous oil products. For example, a heavy lubricating oil may be condensed in tower 5, an intermediate lubricating oil in tower 6, a light lubrieating oil in tower 7 and a gas oil in tower 8. Vapors escaping uncondensed from tower e may be condensed as a napht-ha in the condenser 9.

The following example will illustrate an operation embodying the invention, as cai'- ried out iii-apparatus of the type illustrated: (lult coast crude oil is supplied to the oil heater 2 at a rate of about 10,500 gallons per hour and discharged Jfrom the oil heater at a temperature of about 7 :E0-800 F. An aqueous solution of caustic soda, 25 B., is supplied to the lower end of tower 4 at a rate ot about. 150-250 gallons per hour. The telnperature at the bottom of tower 3 is maintained at about l720 F. and at the top at about 700 F.; the temperature at the boty430 F.; and the temperature at the bottom of tower 8 is maintained at about 400 F. and at the top 'at about 330 F. Crude oil to be distilled is circulated through the cooling coils in the upper ends of the several towers and thus preheated. Superheated steam at a temperature in the neighborhoodv ot' 900 F. is supplied to the lower ends of the several towers at rates regulated to maintain the temperatures mentioned. heated steam at 900 F. is, for example, supplied to the lower ends of towers 3 and 4 at a combined rate approximating 1-3 pounds per gallon of crude oil supplied to the heater. The crude oil may thus be separated, for example, nto a residuum, about 10%, discharged through cooler 110, a caustic bottoms, about 3%discharged through cooler 11, a heavylubricating oil, about 10%, discharged through cooler 12, an intermediatelubricating oil,'about 20%, discharged through cooler 13, a light lubricating. oil, about 13%, discharged through colez 14, aj gas oil, about 35-40%, discharged through cooler 15, and a naphtha discharged through condenser 9.

The operation just described makes possible the direct production from Gulf coast crudes, for example, of distilled lubricating oil products which,`without .further refining treatment, are of good color and stability.

combining with the operation just described Supert a relatively light treatment with sulphuric acid, lubricating oils of extreme stability and having viscosities upwards of 370 at 100 F. and of 2 color or better may be produced. The lubricating oils so produced are of high quality with respect to all the usual requirements, Conradson carbon test, emulsibility test, etc.

We claim:

l. In the manufacture of distilled lubricating oils from petroleum stocks, the'improvement Which comprises flowing a stream of the stock through a heating zone into a vapor separating zone, heating the stock to a va' porizing temperature in the heating zone, separating the vapors and liquid oil in the vapor separating zone, passing the vapors separated in the vapor separating zone through a hot liquid oil bath maintained alkaline by supplying caustic alkali thereto, subjecting the vapors escaping from the Y hot alkaline oil bath to a fractionating oper-ation and condensing high boilin'gconstituents therein, taking 0H vapors from 25' the fractionating operation and condensing a plying caustic alkali thereto, subjecting the vapors escapin from the hot alkaline oil bath to a fractionating operationQ and condensing high boiling constituents therein,

v taking off vapors from the fractionating operation and condensing a lubricating oil fraction therefrom.

3. In the manufacture vof distilled lubri- Icating oils from petroleum stocks, the im` provement which com rises owing a stream of the stock through a 'eating zone into a vapor separating zone, heatin the stock to Va vaporizing temperature in t e heatin zone,

introducing superheated steam into t e val por separating zone, separatingthe vapors and liquid oil in the vapor separating zone, passing the vapors separated in the vapor separating zone through a hot liquid ollbath maintained alkaline by supplying caust1c alkali thereto, subjecting the vapors escaping from the hot alkaline oil bath to a fractionating operation and condensin high boiling vconstituents therein, taking o vapors from the fractionating operation and condensing a lubricating oil fraction therefrom.`

4. In the manufacture of distilled lubricating oils from petroleum stocks, the improvement which comprises fiowing a stream Vof the stock through aheating zone into a vapor separating zone, heating the stock to a vaporizing temperature in the heating zone, introducing a gaseous distillation medium into the vapor separating zone at a temperature higher than that at Whichftheoil leaves the heating zone, separating the vapors and liquid oil in the vapor separating zone, passing the vapors separated in the vapor separating zone through a hot liquid oil bath maintained alkaline by supplying caustic alkali thereto, subjecting the vapors escaping from the hot alkaline oil bath to a fractionating operation and condensing high boiling constituents therein, taking olf vapors from the fractionating operation and condensing a lubricating oil fraction therefrom.

5. In the manufacture of distilled lubricating oils from petroleum stocks, the improvement which comprises flowing a stream of the stock through a heating zone into a vapor separating zone, heating the stock t0 a vaporizing temperature in the heating zone, separating the vapors and liquidoil in the vapor separat-ing zone, passing the vapors separated in the vapor separating zone through a hot liquid oil bath maintained alkaline by supplying caustic alkali thereto,

Isubjecting the vapors escaping from the hot 9 rov alkaline oil bathto a fractionating operation and condensing high boiling constituents therein, taking ofi' vapors` from the fractionating operation and fractionally condensing a lubricating oil fraction therefrom. v

In witness whereof, We have subscribed-l our names. p,

'EUGENE C. HERTHEL. HARRY L. PELZERV.y 

